docs: def function(name, *args, **kwargs):
      """ Construct a parser for a standard function format """
      if kwargs.get("caseless"):
          name = upkey(name)
      else:
          name = Word(name)
      fxn_args = None
      for i, arg in enumerate(args):
          if i == 0:
              fxn_args = arg
          else:
              fxn_args += Suppress(",") + arg
      if fxn_args is None:
          return name + Suppress("(") + Suppress(")")
      if kwargs.get("optparen"):
          return name + ((Suppress("(") + fxn_args + Suppress(")")) | fxn_args)
      else:
          return name + Suppress("(") + fxn_args + Suppress(")")